Final answer:
The word that best completes the sentence is 'publicidades'. It means 'advertisements' in English and refers to rock concert ads.
Step-by-step explanation:
The word that best completes the sentence is publicidades. 'He visto publicidades de conciertos de rock en la televisión.' In this sentence, 'publicidades' means 'advertisements' in English. The phrase 'de conciertos de rock' provides context and indicates that the advertisements are related to rock concerts.
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